Permonosulfuric acid treatment of wool, for shrink resistance



United States Patent PERIVIONOSULFURIC ACID TREATMENT OF WOOL, FOR SHRINK RESISTANCE Eric Tom Fell, Ambergate, England, assignor to Stevenson (Dyers) Limited, Derbyshire, England, a British company No Drawing. Application May 24, 1951, Serial No. 228,143

7 Claims. (Cl. 8-128) This invention relates to the treatment of wool for the purpose of reducing its tendency to felt or shrink when washed in aqueous liquors.

It is known that many oxidising agents have the property of reducing the tendency of wool to felt or shrink, and can be used for this purpose if suitable conditions are selected to avoid damage to the fibres. It is also known that permonosulphuric acid will impart a certain degree of shrink resistance, but no method has hitherto been known of avoiding obvious damage to the fibres when using it.

The object of the present invention is to provide a method whereby wool may be treated with permonosulphuric acid to produce a shrink-resisting finish without obvious damage to the wool, and retaining a handle and colour similar to those of the original wool.

According to the invention, woollen materials are treated at any suitable stage of manufacture with a solution of permonosulphuric acid or a salt or salts thereof, said solution having a pH which is not within the range of from 2 to 7, and, if the pH is below 2, containing not less than 10% by weight of sulphuric acid.

According to a further feature of the invention, the treatment solution is prepared by treating a solution of permonosulphuric acid with alkali so as to obtain a pH greater than 7.

The duration of treatment required varies according to the temperature and concentrations of chemicals used. Thus low concentrations or low temperatures require a more prolonged treatment but by readjustment of these factors the time of treatment necessary may be reduced to a few seconds only. The process is therefore also applicable to continuous processing techniques as well as the more common intermittent or batch techniques now prevalent.

The treatments may be made at temperatures ranging from cold to 50 C. according to the requirements of the goods to be treated, the higher temperatures requiring more rapid passage of the goods through the treating liquor.

The solutions are stable and do not lose strength rapidly during use thus permitting of easy control and uniformity of treatment provided the mechanical presentation of the material to the liquor is adequate.

Example 1 20 parts of an all-wool-fabric are treated for 40 seconds at 33 C. in a bath containing 4 parts of permonosulphuric acid together with 280 parts of water and 120 parts by weight of sulphuric acid, and the fabric is then well rinsed with water.

The resultant fabric possesses a good handle and a good colour without any obvious damage to the wool, and a standard milling test shows that the treated fabric possesses a good shrink resistance when compared against the original fabric.

Example 2 90 parts by weight of wool are treated for minutes at 20 C. in a solution containing 12 parts of permonosulphuric acid together with 1450 parts of water and 820 parts by weight of sulphuric acid and the wool is rinsed well with water.

Example 3 30 parts of wool yarn are treated cold for 1 hour 2,701,178 Patented Feb. 1, 1955 Example 4 30 parts of an all wool fabric are treated cold for 30 minutes in 1000 parts of water containing 3 parts of permonosulphuric acid together with a suitable amount of caustic soda so that the treating bath is initially pH 10.0.

The fabric treated in the above manner shows good shrink resistance when given a standard milling test.

What I claim is:

1. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors, comprising treating such materials with a solution containing a substance selected from the group consisting of permonosulphuric acid and salts of permonosulphuric acid, said solution having a pH in the ranges below pH 2 and between pH above 7 and not over about 11.2, said solution containing not less than 10% by weight of sulphuric acid at the pH range below 2.

2. A method as claimed in claim 1, in which the treatment solution is solution of the sodium salt of permonosulphuric acid having a pH of not over about 11.2.

3. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors, comprising treating such materials with a solution containing 4 parts of permonosulphuric acid and parts of sulphuric acid in 280 parts of water, for 40 seconds at 33 C.

4. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors, comprising treating such materials with a solution containing 12 parts of permonosulphuric acid and 820 parts of sulphuric acid in 1450 parts of water, for 5 minutes at 20 C.

5. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors, comprising treating such materials with a solution containing in 1000 parts of water, 2 parts of permonosulphuric acid and sufficient caustic soda to make the pH initially 11.2 for 1 hour in the cold.

6. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors, comprising treating such materials with a solution containing in 1000 parts of water, 3 parts of permonosulphuric acid and sufficient caustic soda to make the pH initially 10.0 for 30 minutes in the cold.

7. A method of treating materials composed at least partly of wool in order to reduce the tendency of the wool to felt and shrink when washed in aqueous liquors comprising treating such materials with a solution of permonosulphuric acid having a pH below 2, and containing at least ten percent by weight of sulphuric acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,106,107 Parish Aug. 4, 1914 2,173,040 Muller Sept. 12, 1939 2,369,399 MacMahon Feb. 13, 1945 FOREIGN PATENTS 451,115 Great Britain July 29, 1936 451,026 Great Britain July 27, 1936 784,828 France July 25, 1935 798,566 France May 20, 1936 561,521 Germany Oct. 15, 1932 

1. A METHOD OF TREATING MATERIALS COMPOSED AT LEAST PARTLY OF WOOL IN ORDER TO REDUCE THE TENDENCY OF THE WOOL TO FELT AND SHRINK WHEN WASHED IN AQUEOUS LIQUORS, COMPRISING TREATING SUCH MATERIALS WITH A SOLUTION CONTAINING A SUBSTANCE SELCTED FROM THE GROUP CONSISTING OF PERMONOSULPHURIC ACID AND SALTS OF PERMONOSULPHURIC ACID. SAID SOLUTION HAVING A PH IN THE RANGES BELOW PH 2 AND BETWEEN PH ABOVE 7 AND NOT OVER ABOUT 11.2, SAID SOLUTION CONTAINING NOT LESS THAN 10% BY WEIGHT OF SULPHURIC ACID AT THE PH RANGE BELOW
 2. 